lkml.org 
[lkml]   [2017]   [Aug]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v6 1/3] perf/core: use rb trees for pinned/flexible groups
On Mon, Aug 07, 2017 at 07:27:30PM +0300, Alexey Budankov wrote:
> On 07.08.2017 18:55, Peter Zijlstra wrote:

> > In the extreme, if you construct your program such that you'll never get
> > hit by the tick (this used to be a popular measure to hide yourself from
> > time accounting)
>
> Well, some weird thing for me. Never run longer than one tick?
> I could imaging some I/O bound code that would fast serve some short
> messages, all the other time waiting for incoming requests.
> Not sure if CPU events monitoring is helpful in this case.

Like I said, in extreme. Typically its less weird.

Another example is scheduling a very constrained counter/group along
with a bunch of simple events such that the group will only succeed to
schedule when its the first. In this case it will get only 1/nr_events
time with RR, as opposed to the other/simple events that will get
nr_counters/nr_events time.

By making it runtime based, the constrained thing will more often be
head of list and acquire equal total runtime to the other events.

\
 
 \ /
  Last update: 2017-08-07 18:58    [W:0.089 / U:1.872 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site